1. Field of the Invention
The present invention relates to optical data transmission apparatus including low-speed interface units, and in particular, to a method for automatically discriminating low-speed interface units installed in the optical data transmission apparatus together with automatically confirming the installation of the low-speed interface units that are occasionally installed in the optical data transmission apparatus in compliance with data newly required to be transmitted through the optical data transmission apparatus.
2. Description of the Related Art
FIG. 1 shows a block diagram of typical optical data transmission apparatus of the related art, citing an instance of optical data transmission apparatuses 100 and 200 provided in stations A and B respectively. Stations A and B are placed opposite to each other at a distance as far as 50 km, and data transmission is performed between the stations through the distance by using optical transmission means.
The optical data transmission apparatus 100 in station A comprises a signal transmitter 101, a signal receiver 102 and a control unit 103. As in same as optical data transmission apparatus 100, optical data transmission apparatus 200 in station B comprises a signal transmitter 201, a signal receiver 202 and a control unit 203. The signal transmitter 101 includes input type low-speed interface units (IIU) 1, a multiplexing unit (MUX) 2 and an optical signal sending unit (OS) 3, and same as signal transmitter 101, signal transmitter 201 includes IIU 7, MUX 8 and OS 9. The signal receiver 102 in station A includes an optical signal receiving unit (OR) 13, a demultiplexing unit (DMUX) 12 and output type low-speed interface units (OIU) 11, and same as signal receiver 102, signal receiver 202 includes OR 4, DMUX 5 and OIU 6. In the above, IIUs 1 and 7, and OIUs 11 and 6 comprise the same number of units respectively, and the units in IIU 1 correspond to the units in OIU 6 and the units in IIU 7 correspond to the units in OIU 11 in regard to the sorts of the data to be transmitted, respectively. The stations A and B are transmissively connected so that an optical signal from OS 3 in signal transmitter 101 is sent to OR 4 in signal receiver 202 through an optical transmission line 301 and the optical signal from OS 9 in signal transmitter 201 is sent to OR 13 in signal receiver 102 through an optical transmission line 302.
Generally, data sent between stations, like stations A and B, are divided into two categories. One is a data, which will be called a "payload data" hereinafter, required by a client to send between the stations; and the other is a liaison data, which will be called "control data" hereinafter, used for maintaining and/or controlling the optical data transmission apparatus in the stations. The payload data are transmitted on a plurality of ordinary channels and the control data is usually transmitted on an overhead bit (OHB) channel.
In FIG. 1, payload data are transmitted between stations A and B as follows: payload data to be sent from station A to station B are sent to the units (UNIT-1 to UNIT-n) of IIU 1 in signal transmitter 101 in compliance with the sort of the payload data and interfaced respectively so as to be multiplexed by the following MUX 2; a multiplexed signal from MUX 2 is sent to OS 3 and converted to an optical signal; the optical signal from OS 3 is transmitted through the optical transmission line 301 and received at OR 4 in signal receiver 202; the optical signal received at OR 4 is converted to an electric signal and sent to DMUX 5; the electric signal sent to DMUX 5 is demultiplexed; and a demultiplexed signal from the DMUX 5 is sent to the units (UNIT-1' to UNIT-n') of OIU 6 so as to be interfaced to the payload data respectively.
Concretely explaining the above by citing an instance of transmitting telephone signals, the telephone signals are transmitted from station A to B as follows: 45 megabit/sec (Mb/s) data produced by multiplexing telephone signals at telephone switchboards, not depicted in FIG. 1, are sent to the units (UNIT-1 to UNIT-n) of IIU 1 and interfaced, for instance, inverted from bipolar signals to unipolar signals; the interfaced (unipolar) signals from IIU 1 are sent to MUX 2 and multiplexed to 1.8 gigabit/sec (Gb/s) data thereby; the 1.8 Gb/s data (multiplexed signal) is sent to OS 3 and converted to an optical signal; the optical signal from OS 3 is transmitted to OR 4 in signal receiver 202 through the optical transmission line 301; the optical signal is converted to an electric signal at OR 4; the electric signal from OR 4 is demultiplexed by DMUX 5; and the demultiplexed signals from DMUX 5 are sent to the units (UNIT-1' to UNIT-n') of OIU 6 and interfaced to the 45 Mb/s data respectively.
The transmission of payload data are performed from station B to A same as the above. That is: payload data sent to signal transmitter 201 are interfaced by IIU 7; interfaced signals from IIU 7 are multiplexed by MUX 8; a multiplexed signal from MUX 8 is sent to OS 9 so as to be converted to an optical signal; the optical signal from OS 9 is transmitted to OR 13 in signal receiver 102 through optical transmission line 302; the optical signal received at OR 13 is converted to an electric signal and demultiplexed by DMUX 12; and the demultiplexed signals from DMUX 12 are sent to OIU 11 and interfaced to the payload data.
In the above transmission of the payload data between stations A and B, the numbers of units of IIU 1 and OIU 6 and of IIU 7 and OIU 11 are determined by sorts of payload data. Therefore, when other new sorts of payload data are required to be sent between stations A and B, units corresponding to the new sorts of payload data must be installed to IIUs 1 and 7 and OIUs 6 and 11 respectively.
In FIG. 1, it is looked as if the number of units in each IIU and OIU is "n". However, a unit depicted by a dotted box marked by subsidiary numbers "k" in IIUs 1 and 7 or "k'" in OIUs 6 and 11, for example UNIT-k in IIU 1 or UNIT-k' in OIU 6, represents a unit to be newly installed in compliance with a required new sort of payload data, so that the number of units installed in each IIU and OIU is "n-1" before newly installing the unit marked by "k" or "k'" thereto. The unit marked by "k" or "k'" will be called the "UNIT-k" or "UNIT-k'" respectively hereinafter. In other words, FIG. 1 shows a case that each IIU and OIU has n positions of units to be installed and has n-1 positions of units having been installed.
In FIG. 1, when a payload data corresponding to UNIT-k is required to be sent between stations A and B, UNIT-k must be installed in IIUs 1 and 7 respectively and UNIT-k' must be installed in OIUs 6 and 11 respectively. The installation of the UNITs-k and UNITs-k' is performed by a field installer individually at stations A and B. In the related art, after the installation is over at stations A and B, confirmation whether the installation is performed correctly is performed by a professional operator of the control units 15 and 25. When the installation is confirmed so as to be done correctly, all the units installed in IIUs and OIUs in stations A and B are started by the operators at stations A and B. Such discrimination and confirmation of the units of IIUs and OIUs performed in stations A and B are the subject of the present invention. That is, in the related art, the confirmation of the installation has been performed by operators, manually treating control units 103 and 203 individually in stations A and B. Different from the above related art, in the present invention, the discrimination and confirmation are performed automatically by a discriminating system including improved control units in stations A and B. The details of the related art will be explained, citing an instance of station B in reference to FIG. 2.
In FIG. 2, the same reference numeral or symbol as in FIG. 1 designates the same apparatus or unit as in FIG. 1. Every unit of OIU 6 and that of IIU 7 have code data corresponding to a sort of payload data. For instance, cord "09" is used for DS3 interface and cord "03" is used for DS1/DS2 convert module interface; wherein, DS3 and DS1/DS2 convert modules are well known as the typical interfaces, in American National Standard for Telecommunications.
After UNIT-k and UNIT-k' are newly installed in IIU 1 and OIU 11 respectively in optical data transmission apparatus 100 and in IIU7 OIU 6 and IIU 7 respectively in optical data transmission apparatus 200 by the field installers in stations A and B respectively, the professional operators confirm whether the UNITs-k and UNITs-k' are installed in correct positions in stations A and B. In the related art, the discrimination and confirmation are performed in station B as follows: in FIG. 2, the control unit 203 includes a micro processing unit (MPU) 203-1; under operation, which is performed by the operator in station B, of terminal board 25 in station B, MPU 203-1 sends selecting signals (SEL-1' to SEL-n') to OIU 6 and selecting signals (SEL-1 to SEL-n) to IIU 7 respectively in a polling cycle such as 0.5 sec, for polling the code data of units installed in OIU 6 and IIU 7. The polled code data from OIU 6 and IIU7 are sent back to MPU 203-1 through data buses DB-1 and DB-2 respectively and displayed on a display unit, not depicted in FIG. 2, provided to terminal board 25; the operator in station B operates terminal board 25 for discriminating and confirming whether the install positions of UNIT-k' in OIU 6 and UNIT-k in IIU 7, observing the display unit; and if the positions are confirmed so as to be correct, the operator operates MPU 203-1 through terminal board 25 so that the units of OIU 6 and IIU 7 start to operate by start signals START-1' to START-n' and START-1 to START-n sent from MPU 203-1 to OIU 6 and IIU 7 respectively. Same as the above, in station A, the discrimination and confirmation of the units installed in IIU 1 and OIU 11 and re-starting the units if the confirmation results are correctly performed by the operator in station A, observing the indicator unit and operating MPU in control unit 103 through terminal board 15. Thus, in the related art, the discrimination and confirmation of the units installed in IIU and OIU and re-starting the operation of the units must be performed by manually operating the MPU in the control unit through the terminal board at each station, which has been too much complicated to a field worker for installation, who will be called a "field installer" hereinafter. Accordingly, in the related art, the professional operator who can treat the MPU through the terminal board is required to be dispatched to each station.
In addition to the problem mentioned above, there is another problem for the field installer. In case of FIGS. 1 and 2, UNITs-k and UNITs-k' are newly installed in IIUs and OIUs in stations A and B respectively in compliance with the transmission of a new sort of payload data. This means that there are some spare positions for installing the new units of IIU and OIU in FIGS. 1 and 2. However, it occurs that even though all positions for the units are occupied, still other units are required to be installed in IIUs and OIUs in compliance with other sorts of payload data. Usually, MUX and DMUX have sections corresponding to the sorts of the payload data. Therefore, when there is possibility of transmitting new sorts of payload data, sections corresponding to the new sorts of payload data are previously provided in MUX and DMUX and switching units for selecting the sections are provided in MUX and DMUX or in IIU and OIU.
FIG. 5 shows a case of providing a switching unit 61 in OIU 6 and a switching unit 71 in IIU 7 in station B. In FIG. 5, the same reference numeral or symbol as in FIG. 2 designates the same unit or station as in FIG. 2. In the related art, switching unit 61 includes switching elements SW-1' to SW-n' and switching unit 71 includes switching elements SW-1 to SW-n, and switching units 61 and 71 communicate to each other. FIG. 5 shows a case that three sections are provided in DMUX 5 and MUX 8 respectively, corresponding to three sorts of payload data to be interfaced by each unit of OIU 6 and IIU 7. For example, when the switching element is switched to connect with an upper position as shown in SW-1' or SW-1 in FIG. 3, the payload data is a sort of data to be interfaced from DS 1 to VT 1.5. When the switching element is switched to connect with a middle position as shown in SW-2' or SW-2 in FIG. 3, the payload data is a sort of data to be interfaced from DS 1 to DS 2. When the switching element is switched to connect with a down position as shown in SW-k' or SW-k in FIG. 3, the payload data is a sort of data to be interfaced from a bipolar signal to a unipolar signal in DS 3. When signals mentioned above are output from DMUX 5 and input to MUX 8 respectively, UNIT-1' to UNIT-n' in OIU 6 and UNIT-1 to UNIT-n in IIU 7 are installed so that each of the units corresponds to respective sort of signal. Each unit of OIU 6 and IIU 7 has a data code corresponding to the sort of payload data. Therefore, in the related art, when the units of OIU 6 and IIU 7 are installed to corresponding to the sorts of payload data, MPU 203-1 in control unit 203 gathers the data code from the units in OIU 6 and IIU 7 to MPU 203-1 through data buffers DB-1 and DB-2 respectively and sends switching signals to SW-1' to SW-n' in SW 61 and to SW-1 to SW-n in SW 71 respectively so that the switch elements are connected to the sections of the DMUX 5 and MUX 8 so as to correspond to the units in OIU 6 and IIU 7 respectively. Thus, in the related art, the switching is performed automatically by MPU 203-1. However, there has been a problem that if a wrong unit is installed in OIU 6 or IIU 7 because of a mistake due to the field installer, the switching is performed in accordance with the wrong code data from the wrong unit automatically by MPU 203-1, so that wrong connection is performed by a switching element, however nobody knows about the wrong connection.